Compressor



H. w. Dow

COMPRESSOR Filed July 6, 1936 March 30, 1937.

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Patented Mar. 30, 1937' UNITED STATES PATENT.' carica 1.01am comassoa Herbert W. Dow, Milwaukee, Wis., assigner to c Nordberg Manufacturing Company, Milwaukee,

Wis., a corporation of Wisconsin Application July 6, 1936, Serial No. 89,181

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This invention relates to compressors and particularly to unloading devices therefor.

The invention produces an unloader in which the housing for the inlet valve is itself a valve,

and is shiftable to (1) interpose the inlet valve v ance pockets successively with the working space,

but a single pocket per working space is suillcient to disclose the invention and is chosen for description because it is simpler. An important feature of the invention is the adaptation to use, according to the invention, of inlet valves of the type disclosed in the patent to Nordberg, No. 1,570,392, granted January 19, 1926.

The invention when applied with one clearance pocket for each working space of a double-acting compressor unloads in flve steps as follows:

Full capacity.-(Both ends fully loaded). Both clearance pockets isolated, by-passes closed.

3A capacity-(One end fully. the other half loaded). One clearance pocket isolated and the other connected with its working space. Bypasses closed.

1/2 capacity-(Both ends half loaded). Both clearance pockets connected with their working 35. spaces. By-passes closed.

1/4 capacity-(One end half loaded, the other fully unloaded). One clearance pocket connected with its working space and corresponding bypass closed-other by-pass open.

Fully unloaded- Both by-passes open.

Such an embodiment of the invention is illustrated in the accompanying drawing, in which,-

Fig. 1 is a view partly in elevation and partly in section, showing the unloader set for 3A capacity. c

Fig. 2 is a fragmentary view showing the crank end inlet valve housing set to open the bypass.

Fig. 3 is a fragmentary perspective view of the head inlet valve housing or sleeve.

In the drawing, 6 represents the cylinder cast as a unit with jacket 1 and two clearance pockets, namely, a crank end pocket 8 and a head end pocket 9. The ends of the cylinder are closed by heads II and I2 with inlet passages I3 and I4 respectively. The heads are jacketed and Iiacket spaces appear at I9. Discharge connections are 4shown at I6 and lead from the discharge valves of any suitable type (not shown). A rod I1 carries piston I9 which is reciprocated in the cylinder 9 by any suitable means such as the usual crank and connecting rod (not shown).

Swiveled in openings in heads II and I2 respectively are cylindrical housings 2| and 22 for the inletvalves. These housings each have seat grids 23, guard grids 2l, leaf or reed valves 2l and leaf springs 26 constructed substantially according to the disclosure of the Nordberg patent above identified.

Sleeve 2i controls inlet passage Il, passage 21 leading to pocket 9 and passage 28 leading to the icrank end working space in cylinder 6. Sleeve 22 controls inlet passage I4, passage 29 leading to pocket 9 and passageV ll leading to the head end working space in cylinder 8.

Sleeve 2I is shifted by a crank l2 and sleeve 22 by a crank 33. Each sleeve has three positions and the center lines for the cranks are indicated in broken lines for the three positions which each sleeve. assumes.

In Fig. 1 the sleeve 22 is shown in full loading position, so that port 29 leading to -clearance pocket 9 is blanked and the inlet valve is interposed between passages Il and 3l. In Fig. 1 sleeve 2I is shown in half loaded position in which passages 21 and 28 freely communicate, so that the inlet valve is interposed between passage I3 on the one hand and the connected working space and clearance pocket on the other hand. In Fig. 2, sleeve 2| is shown in fully unloaded position so that passages Il, 21 and 28 freely communicate. Each sleeve may assume each of the three positions'.

Each sleeve may be set in each of its three described positions by a corresponding duplex piston motor comprising an outer cylinder, a differential pistnworking therein and forming a cylinder for a second differential piston. The smaller lareas of the two differential pistons are constantly subject to fluid pressure and hence are biased in a downward direction. The admission of pressure fluid against the larger area of either piston overcomes the bias of such piston. When both pistons are down the working space is fully loaded; when one piston alone is up, the working space is partially unloaded and when both pistons are up the working space is fully unloaded.

The duplex piston motors A and B are identical (but'reversed left to right as shown). Hence In motor B cylinder I5 is mounted on` base Il which serves as a cylinder head. In the motor is 5 a diilerential piston made up o! the two-diameter sleeve I1 and head t8 bolted thereto. Sleeve 31 forms a cylinder in which the two-diameter pis.- ton' I8 works. Packing rings are used as indicated. Connecting rods 40 connect pistons Il l with respective cranks 32 and I3.

The smaller (annular) working space 4I on the upper side or the outer piston and the smaller (annular) working space 42 on the upper side of the inner piston are constantly connected by port A pipe 44 leads from the receiver (not shown) charged by the compressor. An auxiliary receiver 45 is charged through check valve 4t from this pipe, and is in free communication via pipe 41 and branches 48 with chambers 4I and 42, so that both pistons are given a yielding bias downward.

Pipe 44 leads to the lower end of a regulator cylinder and valve chest Il beneath a combined piston and, valve 52 which is urged downward by weight l2 adjustably mounted on lever 54. Lever 54 is fulcrumed at i! and reacts on piston 52 through thrust rod i6.

The valve portion of piston 5i is of the balanced piston type and comprises an annular recess 51 and an annular recess 58 which respectively control inlet and exhaust functions, separated by the valve rib l! which has a substantially zero lap with respect 'to each of a series of ports leading to the four lower working spaces of the duplex motors A and B. Hence these ports are either connected to supply or exhaust. A slight positive lap is permissible and probably desirable.

The ports just mentioned are serially arranged so as to be controlled successively, one port Il 40 leading via pipe 62 to the space beneath the outer piston of motor A; port 63 leading via pipe 84 to the corresponding space of motor B; port Il leading via pipe 66 to the space beneath the inner piston of motor A, and port 01 leading via pipe El to the corresponding space of motor B.

Observe that pipes 66 and 68 lead to annular spaces 69 formed around-the outer piston sleeve I1 and thence via ports 1| to the space below the inner piston 20. i

The recesses Bland. connect ports Si, t3, 65 and t1 each selectively with supply port 12 to which pipe 41 leads and with exhaust port 13 with which exhaust pipe 14 connects.

Thus as pressure in the main receiver rises plston i2 moves up and admits pressure successively to the working spaces of motors A and B, so that the outer piston of A rises, then the outer piston oi' B, then the inner piston of A, and nally the inner piston of B. On falling receiver pressure the working spaces are successively vented in reverse order, causing the pistons to descend in reverse order.

To ail'ord increasing resistance to rise of piston I2, it is arranged to pick up successively four 5 weights 1s, 1s, 11 and 1s, Just prior to the opening to supply ot each of the ports Il, 6I, 65 and 61 respectively. 'Ihe weights 15 to 18 inclusive are normally held in suitably spaced relation by a 70 stepped support 1l as shown.

'Ihe exhaust pipe 14 may simply lead to atmosphere but in some cases it is desirable to start the compressor fully unloaded. This is desirable, tor example. when the compressor is driven by a 75 synchronous electric motor. To provide for complete unloading receivery athree-way valve Il isi'nterposedin exhaustpipe 14 connected by branch. with'pressm'e pipe.

In the normal position shown valveV 5 pipe 14 to atmosphere and blanks branch l2. In unloading position (indicated in dotted` lines) it disconnects pipe 14 from atmosphere and oonnects vit with pressure branch I2.' This admits pressure beneath all tour pistons of the motors A l0 andB by way oi' the exhaust passages sothat y these motors move to unloading position. The valve Ii might be manually operated, but is shown with a solenoid motor Il, which can be controlled by a push button on the starting panel 15 or may be included in one of the starting circuits so as to shift the valve Il automatically tounloadlng position during starting and return it to normal position as soon as normal running conditions are attained. o 9

The operation of the device has been traced in connection with the description. The described arrangement aiIords a simple construction with desirable operating characteristics. More steps can be secured byus'ing plural clearance pockets f5' and additional positions of the valve 'sleeves' to cut them in serially.

Various other modifications may be made within the scope oi' the invention as defined in tbe claims. 4

What is claimed- 1. The combination o! a compressor having a' working space; means forming a"clearanoe pocket; means forming an inlet passage; a combined valve and valve housing controlling com- 35 munication between said working space on the one hand and the clearance pocket and inlet passage on the other hand, said housing being shittable between a ilrst position in which ity disconnects the clearance pocket from the work- 40 ing space, a second position in which it connects the same, and a third position in which it opens a free connection between the working space and the inlet passage; and automatic inlet lvalve means mounted in said housingfforcontrolling 45 'one way ilow from the inlet passage to the working space in said first and second positions.

2. The combination of a compressor having a working space; means forming a clearance pocket; means forming an inlet passage; an eion- 60 gated cylindrical valve housing adapted itself to serve as a valve to control communication between said working space on the one'hand and the clearance pocket and inlet e on the other hand, said housing being rotatable between 55 a irst position in which it disconnects the clearance pocket from the working space, a second position in which it connects the same, and a third v position in which it opens a free connection between the working space and the inlet passage; 00 and a series oi' plate type inlet valves mounted in and associated with ports in said housing ior controlling one way flow, from the inlet. passage to the working space in said ilrst and second positions.

3. The .combination of a compressor having a working space; means yforming a clearance pocket; means forming .an inlet passage .a combined valve and valve housing controlling communication between said working space on the one hand and the clearance pocket and inlet passage on the other hand, said housing being shiitable between a ilrst position in which it disconnects the clearance pocket from the working space, a second position in which it connects the same and a third position in which it opens a free connection between the working space and the inlet passage; automatic inlet valve means mounted in said housing for controlling one way ow from the inlet passage to the working space in said first and second positio-ns; and means responsive to pressure developed by operation of the compressor for shifting said housing between said positions.

4. The combination of a compressor having a working space; means forming a clearance pocket; means forming an inlet passage; a combined valve and valve housing controlling communication between said working space on the one hand and the clearance pocket and inlet passage on the other hand, said housing being shiftable between a rst position in which it disconnects the clearance pocket from the working space, a second position in which it connects the same, and a third position in which. it opens a free connection between the working space and the inlet passage; automatic inlet valve means mounted in said housing for controlling one way ilow from the inlet passage to the working space in said first and second positions; two piston motors telescopically arranged with reference to one another; operative connections between the piston of one of said motors and said housing; and pressure responsive valve means serving in response to variations of pressure developed by the compressor to vent, and to admit pressure to both ,motors, and to vent one motor while admitting pressure to the other, the response of the motors under the three stated conditions serving to shift the housing between its three positions.

5. The combination of a compressor having a working space; means forming a clearance pocket; means forming an inlet passage; a combined valve and valve housing controlling communication between said working space on the one hand and the clearance pocket and [inlet passage on the other hand, said housing being shiftable between a rst position in which it disconnects the clearance pocket from the working space, a'second position in which it connects the same, and a third position in which it opens a free connection between the working space and the inlet passage; automatic inlet valve means mounted in said housing for controlling one way flow from the inlet passage to the working space in said first and second positions; two diierential piston motors, the piston of. one carrying the cylinder of the other; means for constantly subjecting the smaller areas of both pistons to pressure fluid to bias both pistons; means for operatively connecting the piston of said other motor with said shiftable housing; and pressure responsive valve means having three positions and controlling pressure on the larger areas of the diflerenl tial pistons and serving in one position to vent both, in another to vent one and admit pressure iluid tothe other, and in a third to admit pressure fluid to both.

6. The combination of fan unloader havingthree operative positions; two diflerentialpiston motors, the piston of one motor carrying ythe cylinder, of the other; means for constantly subjecting the smaller areas of both pistons to pressure fluid to bias both pistons; means for operatively 'connecting the piston ot said other motor with said unloader; and pressure responsive valve means having three operative positions and controlling pressure on the larger areas of the dif- Ierential pistons, the valve means serving in one position to vent both, in another to vent one and admit fluid to the other, and in a third to admit pressure fluid to both.

7. The combination of a compressor having two working spaces; an unloader mechanism for each working space, each unloader having three operative positions in which, respectively, it fully loads the workingl space, partially unloads the working space, or completely unloads the working space according to the position of the unloader; two unloader motor mechanisms, one for each unloader, such mechanism comprising two piston motors telescopically arranged with reference to one another, and operative connections from the piston of one of said motors to the corresponding unloader; and pressure responsive distributing valve means having ve positions, in the first of which it vents both motors of both units, in the second of which it admits pressure to one motor of one unit and vents the remaining three motors, in vthe third of which it admits pressure uid to one motor of both units and vents the remaining two motors, in the fourth of which it admits pressure fluid to both motors of one unit and one motor of the other unit and vents the remaining unit, and in the fifth of which it admits pressure iluid to both motors of both units.

8. The combination of a compressor having two working spaces; unloading means for each of said working spaces, said unloading means each having three functional positions, in one of which it fully loads the working space, in the second of whichit partially unloads the working space, and in the third of which it completely unloads the working space; two motorvunits, one for each unloader mechanism and each comprising two dierential piston motors, the piston of one motor of each unit carrying the cylinder of the other motor of that unit; means for constantly subjecting the smaller areas of the pistons of all said motors to pressure uid to bias said pistons; means for operatively connecting the piston of said other motor of each unit with pistons of the two motor units, said distributing valve having a ilrst position in which it vents pressure from all four ot said larger areas, a

second position in which it vents pressure uid from three of said larger areas and subjects the fourth to pressure iluid, a third position in which it vents one of said larger areas in each of said motor units and subjectthe other larger area in each of said motor units to pressure, a fourth position in which it subjects three of said larger areas inthe two motor units to pressure and vents the fourth, and a ilfth position in which it subjects all four of said larger areas of the two motor units to pressure.

9. The combination deilned in claim 8, in which the unloader mechanism for each working space comprises a valve housing which carries an automatic inlet valve for the working space, and means forming a clearance pocket, the valve housing havingthree functional positions, in one of whichit isolates the clearance pocket from the workingspace to fully load the compressor, in the second of which it connects the clearance pocket with the working space to partially unload the compresson and in the third of which itopens a bypass around said inlet valve to completely unload the working space.

, HERBERT W. DOW. 

